Sexual maturity and fecundity of largemouth bass (Micropterus salmoides) were studied in Maine. Ovaries and ovarian constituents of 46 female bass are described. Atresia, although present, is not prevalent in mature ovaries. Size-frequency distribution of ova was used to determine ovary maturity. Ovum production per fish of 20 mature bass was determined by a dry-weight method. Individual fecundity ranges from 5,000 to 82,000 ova and varies considerably with the age and size of the fish. Ovum production appears to decline in fish older than 7 years. Regression equations are given describing the relationships between fecundity and age, weight and length. The correlation between fecundity and age is higher than between fecundity and weight or fecundity and length. Weight is more closely correlated to fecundity than is length. Regression equations are graphically illustrated and their use for prediction purposes is shown.